The Relationship between Pain Catastrophizing and Cognitive Function in Chronic Musculoskeletal Pain: A Scoping Review

Objective Chronic musculoskeletal pain (CMP) poses a considerable threat to physical, mental, and financial health worldwide. Beyond physical difficulties, CMP has a pronounced impact on pain behaviors and cognitive function. The purpose of this scoping review was to examine the relationship between pain catastrophizing (PC) and cognitive function in CMP, identify gaps in the literature, and provide future directions for research on the topic. Methods Search strings were entered in the following databases: PubMed, CINAHL, Nursing and Allied Health, Ovid Emcare, PsycInfo, and Scopus. Data from the included articles were extracted thematically based on diagnostic classification and included author(s), year of publication, country, aim, sample, methods, intervention (if applicable), and key findings. Results 30 articles were included after screening. The studied populations included patients with fibromyalgia, chronic low back pain, and CMP. Two studies were designed to assess the relationship between PC and cognition as the primary aim. The included studies demonstrated variable evidence regarding the relationship between PC and cognition. Only four studies included clinically relevant PC populations (i.e., Pain Catastrophizing Scale score >30), and all found significant correlations. Conclusion Although evidence exists for the relationship between cognitive function and PC, there is a lack of rigorous research to indicate the strength of this relationship and the specific cognitive functions affected. The literature lacks appropriate populations needed to investigate clinically relevant PC and is limited by heterogeneous neuropsychological test batteries. Future research should include populations demonstrating the behaviors being studied, intentional analysis of outcomes, and appropriate cognitive tests.


Introduction
Chronic musculoskeletal pain (CMP) poses a considerable threat to the physical, mental, and fnancial health of populations worldwide with approximately one-third of the world's population living with some form of ongoing pain [1].CMP encompasses a wide range of clinical diagnoses including, but not limited to, chronic low back pain (CLBP), whiplash-associated disorder, fbromyalgia, and widespread pain syndromes.As pain becomes chronic, healthcare utilization costs rise, wages are lost, and sufering progresses [2].Of note, an overwhelming number of CMP diagnoses lack defnitive structural disorders or pathology, making this the most poorly managed musculoskeletal condition [3][4][5].As such, CMP appears to have a pronounced impact on many other domains including the cognitive-evaluative and motivation-afective components of pain.However, considering pain as a multidimensional process, it is difcult to assess and determine which specifc characteristics contribute the most to the patient's presentation.In CMP, the cognitive-evaluative and emotional-afective processes such as pain catastrophizing and fear may impact the relationship between pain and cognitive function more than pain intensity alone [6].
Te development of maladaptive pain behaviors, including pain catastrophizing, signifcantly impacts the trajectory of an individual's painful condition in the areas of overall health, quality of life, and functional outcomes.Pain catastrophizing increases the likelihood of greater pain severity, intensity, and disability caused by the painful condition, has been found to account for nearly half of the variance in the likelihood of developing chronic pain in people with CLBP, and is a strong predictor of future pain levels in people with CMP [7].Specifcally, pain catastrophizing is the most common maladaptive pain behavior seen in patients with chronic pain, as approximately 39% of patients with chronic pain report severe pain catastrophizing [8].Pain catastrophizing is defned as "the tendency to magnify the threat value of pain stimulus and to feel helpless in the context of pain, and by a relative inability to inhibit pain-related thoughts in anticipation of, during, or following a painful encounter" [9].Pain catastrophizing is associated with an increase in protective vigilance towards an individual's pain and is known to limit the success of common therapeutic interventions targeting peripheral tissues [10,11].As eforts have been made to target interventions for pain behaviors such as catastrophizing in people with CMP, these intervention efects on pain, quality of life, and function remain modest at best [12][13][14].Targeted cognitivebased interventions have been developed to address these behaviors including choices such as pain neuroscience education (PNE), cognitive-behavioral therapy (CBT), and acceptance and commitment therapy (ACT).While the interventions do appear to have their greatest impact by reducing behaviors such as pain catastrophizing and fear, their efect sizes remain limited.Efects sizes even appear to signifcantly decrease when the level of specifc behaviors reaches certain thresholds rendering the interventions less useful for the same targeted behavior [15,16].Tis may in part be due to the cognitively demanding nature of pain itself as evidence demonstrates that cognitive reserves are diminished by an upregulation of focus on current or anticipated pain [17][18][19].
Cognitive impairments such as defcits in attention, memory, learning, and decision making are present in nearly one-third of patients with chronic pain [20].A 2018 systematic review by Higgens et al. showed a signifcant relationship between the occurrence of chronic pain and the presence of neurocognitive dysfunction, with signifcant, negative correlations between pain and performance on objective neurophysiological tests that assessed memory, attention, processing speed, and executive function (r � −0.301 to −0.698) [6,[21][22][23].Higgens et al.'s fndings support the idea that pain is multidimensional.Te relationship between pain and cognitive function may be infuenced by the afective and evaluative components of pain, such as pain catastrophizing, kinesiophobia, depression, and anxiety.Pain catastrophizing is likely to interfere with the efcacy of cognitive-based interventions as cognitive impairments may limit an individual's ability to amend the deleterious efects of catastrophic thoughts and behaviors [24,25].It has been hypothesized that catastrophizing leads to increased attentiveness towards pain or pain-related information [26][27][28][29].Terefore, the cognitive resources directed towards an individual's pain may leave limited reserves for other cognitively demanding tasks such as participating in cognitive-based interventions.
Although two meta-analyses [30,31] investigating attentional biases towards pain did not fnd specifc relationships between catastrophizing and cognition, these analyses suggest that cognitive defcits may be unique to patients with specifc pain profles, likely including higher levels of pain catastrophizing.Terefore, the lack of efectiveness of cognition-based interventions may be due to the heterogeneity of pain populations.To date, only a few studies have explicitly explored the relationship between pain catastrophizing and cognitive function so as to better understand the potentially dynamic interplay between the two and provide insight into therapeutic targets.Evidence is growing to support the need to determine specifc pain phenotypes that allows for improved assessment and management of CMP.More specifcally, a deeper understanding of psychological phenotypes may help determine the best approach for and mechanisms of cognitivebased interventions [32][33][34].Terefore, the primary aim of this scoping review was to examine the relationship between pain catastrophizing and cognitive function in CMP.Te secondary aim was to identify the limitations of the literature and to provide future directions for research on the topic.

Methods
A scoping review was conducted to systematically identify and synthesize all available literature on the relationship between pain catastrophizing and cognitive function in people living with chronic pain [35].In addition to summarizing literature, a scoping review can identify and map available emerging evidence and can report on the types of evidence in order to address and inform practice and future research [36].Finally, being a scoping review, a thorough assessment of methodological quality or risk of bias was not performed [37].To ensure the rigor of this scoping review, the procedures outlined in PRISMA-Extension for Scoping Reviews were followed [37].Te review was registered with the Open Science Framework (OSF) registry (osf.io/p2cqf ).

Operational Defnitions.
For the purpose of this scoping review, we adopted the following operational defnitions: (1) pain catastrophizing is a cognitive or emotional process encompassing magnifcation of pain-related stimuli, feelings of helplessness, and a generally pessimistic orientation [38], (2) cognition is the process by which the brain acquires, processes, stores, and retrieves information [39], and (3) cognitive function is the performance of the mental process of perception, learning, memory, understanding, awareness, reasoning, judgment, intuition, and language [40].In addition, cognitive function was not defned in the context of pain.

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Pain Research and Management

Eligibility Criteria.
Te following criteria were determined a priori and were used to screen articles for this scoping review: (1) articles in English language, (2) studies that included adults with chronic musculoskeletal pain (defned as >3 months duration), (3) articles that were published from 1995 to 2022, (4) articles of primary sources only, (5) studies that contained an objective measure of pain catastrophizing, and ( 6) studies that contained an objective measure of cognitive function based on the abovementioned operational defnition.Exclusion criteria included (1) studies consisting of experimentally induced pain and (2) nonscholarly products (e.g., magazine articles and editorials).Articles returned were uploaded to the systematic review tool, Rayyan (Rayyan Systems, Inc., Cambridge, MA).Next, Rayyan's duplicate detection tool was used to identify possible duplicates which were then manually inspected and removed where appropriate.Following the PRISMA guidelines [37], two researchers (CA and EB) utilized the "blind" function in Rayyan to independently screen each record by title and abstract and then by full text for its eligibility using the predetermined inclusion/exclusion criteria.When there was a confict between the two researchers, a third researcher (SWP) resolved the conficts.

Databases and Search
After article screens were concluded, the researchers (CA and EB) performed a historical citation search of the included articles references and utilized Google Scholar's "cited by" tool to perform a forward citation search for any additional pertinent articles.Any new pertinent articles were added to the fnal list of the included articles.Te citations included in these articles were also examined.Finally, the articles included in the review were searched for retractions and none were found.

Data Extraction.
Data from the included articles were extracted and thematically organized based on diagnostic classifcation.Data extracted from each article included author(s), year of publication, country, aim, sample (including gender and age distributions when available), methods, intervention (if applicable), and key fndings following the recommendations of the Joanna Briggs Institute's Reviewers Manual (JBI's Reviewers Manual) [41].

Synthesis of Results.
A critical appraisal of study quality was not performed as this scoping review aimed to examine the relationship between pain catastrophizing and cognitive function in CMP and was not intended to examine intervention efectiveness.After initial review of the included articles by diagnostic categories, a second review was performed to investigate diferences in those studies containing populations with clinically relevant pain catastrophizing versus those that did not.Synthesis of the data required an investigation into the outcomes used to measure pain catastrophizing and their cutof scores.Finally, the specifc neuropsychological tests performed in each study were reviewed to determine the proposed cognitive domain assessed.

Results
Figure 1 presents the PRISMA chart for the study selection, the screening process for each phase, and the reasons for study exclusion.After an initial search, 6798 articles were identifed, and following the removal of the duplicates, 4941 articles were screened for eligibility.Consequently, 25 articles were included in this review after the initial screening.A follow-up citation search identifed 98 articles, of which 5 were included for review.Te 30 articles included in this review consisted of two randomized control trials (RCTs) and 28 observational studies.Studies were grouped according to the study diagnosis: 9 studies of fbromyalgia (FM), 10 studies of CLBP, and 11 studies of chronic musculoskeletal pain in other areas than low back.Study characteristics identifed in the data extraction process are presented in Table 2 (FM), Table 3

(CLBP), and Table 4 (CMP).
Te majority (n � 26) of the studies primarily used the Pain Catastrophizing Scale (PCS) [42] to assess the level of pain catastrophizing.However, four studies used the complete, subscale, or modifcation of the Coping Strategies Questionnaire (CSQ) [43], and one study used the Pain Response Self-Statements questionnaire (PRSS) [44].A wide variety of neuropsychological tests were performed to measure cognitive defcits.Te tests used to measure pain catastrophizing and the tests used to measure cognitive impairments and their specifc intended targets (e.g., executive function, attention, and/or memory) are listed in Tables 2-4.[45].For the FM population, one of nine studies by Galvez-Sánchez et al. [46] reported a signifcant relationship between catastrophizing and cognition (execution time, immediate recall, interference control, and recognition).In this study, the patients diagnosed with FM performed poorly on cognitive tests Pain Research and Management compared to healthy controls.Further, higher levels of catastrophizing explained the largest portion of the variance in poor cognitive performance (r 2 � 0.39) [46].Alternatively, a RCT tested a positive psychology Internet intervention versus a control condition and found that although the intervention reduced pain catastrophizing, it did not improve cognitive performance in executive tasks that involve attention, memory, and set shifting [47].No associations were found between catastrophizing and task performance in those with FM in four studies [47][48][49][50].However, the pain catastrophizing level was correlated with the occurrence of self-reported memory complaints in one study [51].De Gier et al. [52] found that pain-related fear with concurrent high levels of pain catastrophizing was a strong predictor of cognitive performance, although there were no statistically strong correlations between catastrophizing and cognition.In addition, Moore et al. found a signifcant diference in attentional interference and catastrophizing between FM patients and healthy controls (p < 0.01), but correlational analyses were not performed to examine their relationship [53].Similarly, Segura-Jiménez et al. reported gender diferences in cognitive function and catastrophizing in this population without analysis of correlation [54].

Fibromyalgia. FM is the most common diagnosis for which researchers investigate pain catastrophizing and impaired cognition
*Consider, if feasible to do so, reporting the number of records identified from each database or register searched (rather than the total number across all databases/registers). **If automation tools were used, indicate how many records were excluded by a human and how many were excluded by automation tools.

Identification of studies via databases and registers
Identification of studies via other methods  ("pain catastrophizing" OR "pain catastrophization" OR catastrophization OR catastrophizing OR catastrophize OR catastrophisation OR catastrophising OR catastrophise OR "pain vigilance" OR "pain rumination" OR "pain magnifcation" OR "pain helplessness") AND ("chronic pain" OR "pain" OR "widespread pain syndrome" OR "fbromyalgia" OR "musculoskeletal pain") AND ("cognitive function" OR "cognitive functioning" OR "cognitive skills" OR "cognitive ability" OR "cognitive abilities" OR "cognitive impairment" OR "executive function" OR "cognitive fexibility" OR "mental abilities" OR "mental ability" OR "cognitive dysfunction" OR "cognitively impaired" OR "executive dysfunction" OR "cognitive adaptability" OR "cognitive rigidity" OR "mental rigidity" OR "cognitive performance" OR "neuropsychological function" OR "cognition" OR "neurocognitive function" OR neurocognition OR "cognitive dissonance" OR "cognitive fexibility" OR "cognitive control" OR "executive control" OR "attention" OR "attentional control" OR "attentional interference" OR "attention defcit" OR "attention bias" OR "focus" OR "concentration") 4 Pain Research and Management         Pain Research and Management 13

Records
3.2.Chronic Low Back Pain.CLBP contributes the most to disabilities related to musculoskeletal disorders and has a signifcant rate of recurrence [1].In two studies, catastrophizing was found to be correlated with poorer cognitive performance (i.e., attention) on objective testing (r � 0.34, p < 0.05) [19,55].Similarly, attentional impairments demonstrated on reaction time tasks were also associated with pain catastrophizing in one study [56] and delayed trunk muscle activation during rapid arm movements in another study [57].Melkumova et al. [58] also found pain catastrophizing to be associated with memory defcits assessed by a battery of cognitive tests in participants aged 51-60 years old (r � −0.495).In contrast, two studies found a signifcant diference in cognitive performance catastrophizing between LBP patients and controls but no signifcant correlation between these variables within the groups [59,60].Crombez et al. found that pain intensity, not catastrophizing, was predictive of attentional interference time [61].One RCT by Baker et al. [62] showed that responders to a computerized cognitive training program had higher baseline pain catastrophizing.Lower self-reported cognitive function was correlated with a reduction in catastrophizing following the 8-week intervention.However, there was no correlation between objective cognitive testing and pain catastrophizing.

3.3.
Other Chronic Musculoskeletal Pain.Tis group of studies (n � 11) was comprised of a population of syndromes or diagnoses that lack specifc explanation as they relate to a defnitive structure or tissue.Four studies found signifcant relationships between a high level of pain catastrophizing and poor cognitive function on a variety of tests [25,[63][64][65].Tree studies [66][67][68] found no association between pain catastrophizing and cognition, whereas four others identifed the frequent presence of these variables together in CMP populations without testing specifc relationships [69][70][71][72].

Discussion
Pain catastrophizing and cognitive dysfunction are common variables associated with CMP.Tese variables are known to negatively infuence the management of the condition, but there is a limited understanding of how they interact to elicit that impact.Te specifc aim of this scoping review was to examine pain catastrophizing and its apparent connection with cognition.Te results of this scoping review revealed no clear conclusions as to the relationship between pain catastrophizing and cognition.Only two studies [60,70] specifcally were designed to investigate this relationship.All other studies only included the relationship between the two variables of interest as secondary aims or included these two variables without primary consideration.Several themes arose during this scoping review including a lack of clinically meaningful pain catastrophizing levels within the study populations, limited utilization of pain catastrophizing subscale assessment, and variation in neuropsychological testing protocols.
Although several studies suggest that pain catastrophizing may impact cognitive performance in pain-free populations [73][74][75][76], the results of this scoping review were not conclusive.Tis may be in part due to the lack of defnitions of clinically relevant levels of pain catastrophizing within the included studies.Te accepted cutofs for "clinically meaningful" pain catastrophizing are ≥30 points on the PCS [42,77], ≥20 points on the CSQ [78], and >3.81 on the PRSS [44,79].Only four studies [46,52,57,65] met the threshold for their respective pain catastrophizing measures, whereas 22 studies [47-51, 54, 56, 58-64, 66-72, 80] reported the mean scores less than the cutofs in their participants, and four studies did not report the mean scores of their pain catastrophizing measures [25,53,81].Without sample means for pain catastrophizing, results from these studies cannot be generalized to determine the relationship between clinically relevant pain catastrophizing and cognitive function.In addition, of the four studies reporting clinically meaningful levels of catastrophizing, three studies [46,57,65] reported negative correlations with a cognitive variable and one demonstrated a trend towards negative correlation [52].Of the eleven studies [47-51, 59-61, 66-68] that reported their participants having a subclinical pain catastrophizing level, only fve reported a signifcant relationship between pain catastrophizing and cognition [56,58,63,64,80], and six studies reported trends but no correlation analyses [54,62,[69][70][71][72]. Tese fndings may highlight an important gap in the literature as a majority of the populations studied lacked clinically relevant pain catastrophizing.Future research with larger sample sizes should investigate the relationship between pain catastrophizing and cognitive function within and between populations with high and low catastrophizing.
Te most widely used outcome measure to capture the clinical presence of pain catastrophizing is the PCS [42].Te PCS provides four scores including a total score and the three subscale scores for rumination, magnifcation, and helplessness.Because the total PCS score can be impacted by its individual domains, it is important to consider the weight of those subdomains as well [9].In addition to a cutof score of 30 for the total score of the PCS, the cutof scores of 11, 5, and 13 also have been determined for the rumination, magnifcation, and helplessness domains, respectively [42].Any score equal to or higher than the cutof scores indicates a signifcant clinical manifestation of pain catastrophizing overall or in the specifc domain.Only three of the studies reviewed included subdomain scores in their analyses [25,54,65], and two studies found signifcant correlations between cognitive performance and PCS total scores, as well as the rumination subdomain [25,65].As the three domains of the PCS represent diferent constructs in the pain experience, the individual domain scores could further specify the areas of cognitive defcits [82].Te individual domain scores perhaps provide clinicians and patients more meaningful insights about their specifc cognitive defcits to better plan an intervention strategy to address the defcits.Tus, the landscape of literature on this topic may paint an incomplete picture as to the relationship between cognitive function and pain catastrophizing when the relevance of individual subdomains is unknown.
One possible explanation for the inconclusive fnding of the relationship between the pain catastrophizing level and cognition performance is due to a wide variety of neuropsychological tests used to assess cognitive function among the studies included in this review [20].Although there are many validated tests for various cognitive functions, few are validated for populations with CMP and the reliability of a test can change when performed as part of a battery of other tests or can be subject to a varied amount of clinical judgment in its scoring [83].Of the 30 articles reviewed, there were 45 different neuropsychological tests performed, none of which were consistently used across all studies.Table 5 displays the tests used in the studies included in this scoping review and sorted by the cognitive function each test is proposed to assess.Attention and memory are the most commonly impaired cognitive functions in patients with chronic pain and were frequently tested in patients with pain catastrophizing [53,84].Te high levels of variability in neuropsychological assessment among the studies in this review make it difcult to generalize the results.As research continues to expand in this area, researchers should state justifcation explicitly for the tests selected, and future studies should consider standardizing cognitive measures used for people living with CMP.
A majority (n � 26) of the studies included predominantly female samples with four of those recruiting only female participants.While the infuence of gender was not a focus of this review, it is important to highlight that CMP does appear to infuence females with greater frequency and severity than it does males [85].Tus, the imbalance of gender within the included studies is not surprising.However, this does limit the ability to generalize fndings across wider groups of people.Lastly, the mean age of study samples ranged from 21.8 to 70.3 years.Only one study included a sample >65 years of age [56] which is a typical cutof used to control for the infuence of agerelated cognitive decline [86,87].

Limitations
Tere are several limitations to this scoping review.Several of the included studies contained small sample sizes and many did not include pain-free comparison groups.Tese factors may limit the generalization of the fndings as well as the ability to infer diferences between CMP and pain-free populations.Although many of the articles included in this scoping review discussed descriptive relationships between pain catastrophizing and cognition, correlational analyses were either not performed or not mentioned.Terefore, there appear to be missed opportunities to demonstrate the relationship between the two variables of interest.Te search strategy and inclusion/exclusion criteria used for this review attempted to limit the addition of studies investigating non-musculoskeletal pain diagnosis.In this process, there is the possibility that certain conditions, syndromes, or diagnoses were excluded based on the use of this term.Although the methods, searches, and review of this study were comprehensive and included blinding, there is potential for bias with retrieval and selection of research.Lastly, there is considerable variability in the defnitions of cognition and its function, and it is therefore possible that certain domains of cognition function were not captured among the studies reviewed.

Conclusions
Tis scoping review shows that although evidence exists for the relationship between cognitive function and pain catastrophizing, there is a lack of rigorous research to indicate the strength of this relationship and the relationship of pain catastrophizing and specifc cognitive defcits.Available literature contains small sample sizes of patients with clinically meaningful levels of pain catastrophizing, making Pain Research and Management it difcult to determine the utility of the results.Tere was also very little consistency in the neuropsychological tests used to investigate cognitive function.Future research should include a more comprehensive population that demonstrates the behaviors being studied, an intentional analysis of outcomes, and appropriate cognitive tests for chronic pain populations.Given the tremendous burden of CMP and its supported relationship with cognitive function, a better understanding of the defcits in specifc cognitive functions will help promote improved clinical management and outcomes in the patient population with pain catastrophizing.Specifcally, if cognitive-based interventions are standard practice in the management of pain behaviors such as pain catastrophizing and cognitive dysfunction is linked to those behaviors, treatment responses may be self-limiting.Tus, identifying psychological phenotypes in CMP patients and understanding appropriate intervention selection, sequencing, and progression based on those phenotypes may increase the likelihood of successful treatment outcomes in the CMP population.

Figure 1 :
Figure 1: PRISMA fow diagram detailing database searches, abstracts screened, and full tests retrieved.

Table 3 :
Chronic low back pain articles.

Table 5 :
Domains of neuropsychological tests.